An 18-fold increase in the anti-drugs budget in the US to $18billion between 1981 and 2002 had failed to stem the market for the drug.

In fact cannabis related drugs arrests in the US increased from 350,000 in 1990 to more than 800,000 a year by 2006, with seizures quintupling to 1.1million kilogrammes.

The editorial, written by Professor Robin Room of Melbourne University, said: “In some places, state controlled instruments – such as licensing regimes, inspectors, and sales outlets run by the Government – are still in place for alcohol and these could be extended to cover cannabis.”